Dynamic boost battery chargers

ABSTRACT

There is disclosed a dynamic boost charging system having a monitoring component configured to measure total DC current and/or battery current and a reporting component configured to transmit output data of the total DC current and/or battery current measured. A battery charger control system in operable connection with the monitoring component receives the data of the total DC current and/or battery current measured by the monitoring component, and is configured to: obtain an initial time and/or charge measurement; determine a time and/or charge to complete a recharge cycle based on the time and/or charge measurement; selectively use at least two preset DC output voltage settings, one of the at least two preset DC voltage settings being a float voltage, and another of the at least two preset DC voltage settings being a boost voltage; and maintain the boost voltage until the time has passed the charge has been provided.

REFERENCE TO PENDING PRIOR PATENT APPLICATION

This application claims the benefit under 35 U.S.C. 119 (e) of U.S.Provisional Patent Application No. 61/823,335, filed May 14, 2013 byTIMOTHY C. GROAT and HERBERT R. KAEWERT for “DYNAMIC BOOST BATTERYCHARGERS,” which patent application is hereby incorporated herein byreference.

BACKGROUND

Generally, modern automatic battery chargers employ one of a number ofcharging methods, such as demand-based automatic boost charging,time-limited demand-based automatic boost charging, fixed extensiondemand-based automatic boost charging, or the like.

Limitations of standard demand-based boost charging systems and methodsinclude that initiation and reversion thresholds must exceed the DC loadon the battery plus the fully charged battery's current at boostcharging voltage. Another limitation is that the initiation andreversion thresholds must allow for battery current variations caused bybattery manufacturing differences, temperature, and aging. Because themethod is not adaptive, another limitation of standard systems is thatthresholds must be selected to avoid over-charging for the severe cases.This results in under-charging in most applications.

Limitations of time-limited demand-based boost charging systems andmethods include the same general limitations as the standarddemand-based boost charging method. The time-limited systems adds abackup means of boost charge termination, limiting the impact ofover-charging if the initiation and reversion thresholds are toooptimistic for the application. Another limitation is the time limit isnot adaptive. It is set to a time that is ideal for only one specificrecharge case and non-optimal for all others.

Limitations of fixed-time-extension demand-based boost charging systemsand methods have the same general limitations as the standarddemand-based boost charging method. It adds a fixed time extension tothe boost charge, for the purpose of achieving a more complete chargefor conservative reversion transition current settings. The limitationis that time extension is not adaptive. The time extension is the sameregardless of battery condition, depth of battery discharge,temperature, etc. The selected value is a compromise betweenover-charging in some cases and under-charging in others. For example,some existing battery charges have a fixed six-hour extension to ademand-based boost charge. Since this time extension is fixed thebattery will be over charged when it is lightly discharged and requiresa shorter boost charge, or it will be under-charged when it is deeplydischarged and requires a longer boost charge.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key aspects oressential aspects of the claimed subject matter. Moreover, this Summaryis not intended for use as an aid in determining the scope of theclaimed subject matter.

In an embodiment, there is provided a dynamic boost charging method,comprising selectively producing a charging current from at least twopreset DC voltage settings with a battery charger control system, one ofthe preset DC voltage settings being a float voltage, and another of thepreset DC voltage settings being a boost voltage; and measuring the DCoutput current produced by the battery charger control system with aninternal monitoring component in operable connection with the batterycharger control system and configured to transmit output data of the DCoutput current measured by the internal monitoring component to thebattery charger control system. Therein, an initial time or chargemeasurement is obtained, a determination is made as to an appropriatetime or charge to complete the recharge cycle, based on thatmeasurement, and boost voltage is maintained for or until the time haspassed or the charge has been provided.

In accordance with embodiments of the present systems and methods fordynamic demand based boost charging, a dynamic charge counter may beinitialized and a boost voltage set, if a float charge current isgreater than an initiation threshold. During a boost charge adetermination may be made as to whether a boost current is greater thanan initiation threshold and a determination may be made whether adynamic charge count limit has been reached, if the boost current is notgreater than the initiation threshold. A predetermined percent overcharge time may be added to the dynamic charge counter and the boostvoltage retained, if the dynamic charge count limit has not beenreached. A determination may be made as to whether the dynamic chargecounter has reached zero, and the boost voltage may be retained if thedynamic charge count has not reached zero and the dynamic charge countermay be decremented. If a boost charge current is less than a reversionthreshold, a determination may be made as to whether a dynamic chargingis enabled. A float voltage may be set if the dynamic charge is notenabled. If the dynamic charge is enabled a determination may be made asto whether the dynamic charge count has reached zero. A float voltagemay be set if the dynamic charge counter reaches zero. Additionally, aboost voltage may be terminated if the boost charge current is greaterthan a reversion threshold for greater than a predetermined time limit.The forgoing methods may be implemented automatically by a processorcontrolled battery charger

Additional objects, advantages and novel features of the technology willbe set forth in part in the description which follows, and in part willbecome more apparent to those skilled in the art upon examination of thefollowing, or may be learned from practice of the technology.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention,including the preferred embodiment, are described with reference to thefollowing figures, wherein like reference numerals refer to like partsthroughout the various views unless otherwise specified. Illustrativeembodiments of the invention are illustrated in the drawings, in which:

FIG. 1 (PRIOR ART) illustrates a flowchart diagram of a standarddemand-based automatic boost charge for an auto-charge system andmethod;

FIG. 2 (PRIOR ART) illustrates a flowchart diagram of a time-limiteddemand-based automatic boost charge for an auto-charge system andmethod;

FIG. 3 (PRIOR ART) illustrates a flowchart diagram of a fixed extensiondemand-based automatic boost charge for an auto-charge system andmethod;

FIG. 4 illustrates a block diagram of a dynamic demand-based automaticboost battery charger, in accordance with at least one embodiment;

FIGS. 5A and 5B illustrate an exemplary flowchart diagram of a dynamicdemand-based automatic boost charge for an auto-charge system andmethod, according to at least one embodiment; and

FIGS. 6A and 6B illustrate an exemplary flowchart diagram of atime-limited dynamic demand-based automatic boost charge for anauto-charge system and method, according to at least one embodiment.

DETAILED DESCRIPTION Overview

Embodiments are described more fully below in sufficient detail toenable those skilled in the art to practice the system and method.However, embodiments may be implemented in many different forms andshould not be construed as being limited to the embodiments set forthherein. The following detailed description is, therefore, not to betaken in a limiting sense.

In various embodiments, dynamic boost charging systems and methods mayprovide more sophisticated and adaptive battery charging as compared toconventional battery chargers and charging system and methods. Invarious embodiments, a battery charging method may be referred to as a“dynamic boost” or “dynamic equalize” and may be used in a regulatedbattery charger. The present battery charging method recharges adischarged, or partially discharged, battery in an efficient manner ascompletely and quickly as possible, and without overcharging thebattery. In various embodiments, the battery charging method may adaptto changing conditions of the battery and its environment.

Embodiments of the dynamic battery charging systems and methodsdescribed herein may be referred to in several different ways,including, but not limited to “dynamic boost,” “dynamic equalize,”“dynamic auto boost,” “dynamic auto equalize,” “dynamic demand-basedauto boost,” “dynamic demand-based auto equalize,” and/or the like.

One of skill in the art will appreciate there is a subtle difference inthe typical usage of the terms “boost” and “equalize”. For enginestarting applications, motive power and similar applications where thecharger's primary function is recharge of a battery and not powering ofa continuous DC load, the term “boost” is typically used to bedescriptive of a rapid recharge after the battery is discharged by adischarge event. In applications where the charger delivers continuousDC power, such as industrial controls, switchgear, inverter ortelecommunications applications, the term “equalize” is typically usedto be descriptive of a higher charging voltage (the equalize voltage),which will cause individual cell voltages to become more nearly equal toeach other by delivering a limited overcharge to the entire string ofcells. In accordance with various embodiments, a battery charger can beplaced into equalize mode manually, or programmed to perform automaticequalize on a periodic basis, for example monthly.

As used herein, the terms “charger” and “battery charger” are intendedto be descriptive of a product that has electrical or mechanical input,output, and user controls. Inputs may include sinusoidal AC input power,DC power or mechanical energy, and provide regulated DC output current.

As used herein, the terms “microprocessor” and “microcontroller” areintended to be as general as possible and refer to an electroniccomponent that has digital (and usually also analog) inputs and outputs.A microcontroller can be implemented using one or more electronicdevices connected together and interconnected with other controlcircuitry inside of a battery charger, in accordance with embodiments ofthe present systems and methods.

As used herein, the terms “timer” and “counter” are intended to be asgeneral as possible. In accordance with embodiments of the presentsystems and methods, a battery charger's timing functions can beimplemented in a microcontroller, thus avoiding use of a separate pieceof hardware that is a timer or that functions only as a timer. However,in other embodiments, the present dynamic demand-based boost chargingsystems and methods may be implemented using other timers such asmechanical counters, clockwork timers, and combinations of such devices.

A typical storage battery can be thought of as an ideal battery inseries with electrical resistance. Maximizing the potential (voltage)difference between a charging source and battery, maximizes the rate atwhich current flows from the charging source into the battery. This highcharging voltage mode is called “boost” charge mode. As the batterybecomes charged the ideal battery accepts decreasing amounts of current.As current diminishes less voltage is lost to heat in the battery'sinternal resistance, exposing the ideal battery to increasing voltagefrom the constant voltage charging source. If not corrected, this excessvoltage would overcharge and damage the battery. This problem isaddressed by switching the charger's output voltage to a lower level ina charging mode called “float”. The “float” mode allows the battery toaccept just enough current to offset its self-discharge rate so as tomaintain the battery at full charge.

A float voltage is set at a level that is appropriate for maintaining afully charged battery. A typical value for float voltage isapproximately 2.2 volts per cell, or 13.2 volts for a “12 Volt” (6 cell)“flooded” or “wet” lead-acid storage battery at a temperature of 25degrees C. During normal float operation of a charger and battery, thecurrent drawn by the battery (the “float current”) should be low(typically less than 0.0025 amperes per ampere-hour battery capacity) ifthe battery is at or near a fully charged state.

The boost voltage is set at one or more different levels higher than thefloat voltage with the objective of recharging a discharged (orpartially discharged) battery faster than the battery would be chargedat the float voltage. Furthermore, the boost voltage is set at a levelbelow a damaging voltage that may charge the battery too rapidly. Atypical value for boost voltage may be approximately 2.4 volts per cell,or 14.4 volts for a “12 Volt” (6 cell) flooded lead-acid storagebattery, at a temperature of 25 degrees C.

Depending on its state of charge, a battery will accept more or lesscurrent from a battery charger that is producing a regulated preset DCoutput voltage. Therefore, for a battery charger that is operating atfloat voltage, a battery will typically draw more current when it is ina discharged state as compared with the “float current” that it willdraw when it is fully charged. Likewise, for a battery charger that isoperating at boost voltage, a battery will typically draw more currentwhen it is in a discharged state as compared with the current that itwill draw when it is fully charged. Furthermore, for any given state ofcharge, a battery will typically draw more current when the batterycharger is at boost voltage as compared with the current draw at floatvoltage.

Herein, descriptions of charging methods are presented within thecontext of a storage battery at a constant temperature of approximately25 degrees C, and therefore will not consider the effects of increasingor decreasing battery (or necessarily ambient) temperature. Variouscharger embodiments that employ the present systems and methods fordynamic demand-based charging may also employ automatic temperaturecompensation. For temperatures that are more than 5 degrees C. higher orlower than 25 degrees C., automatic temperature compensation may be usedthat causes the battery charger's output voltage to be incrementallyhigher at lower ambient temperatures, and incrementally lower at higherambient temperatures. The purpose of temperature compensation is toprevent undercharging and overcharging of the battery.

Embodiments of the present dynamic boost charging systems and methodsrecharge a battery both faster and more safely than a standard boostcharging method. Standard demand-based automatic boost charging methodsare commonplace in the industry. These charging methods use simple rulesfor making transitions between float and boost, in both directions, andthey are not adaptive.

Prior art FIG. 1 illustrates a flowchart diagram of standarddemand-based automatic boost charge for an auto-charge system and method100. Beginning at state selection 110, a determination is made at 120 ofa previous output voltage setting for the charger. If the charger wasoutputting a float voltage (122), then at 130 a determination is made asto whether the current being drawn by the battery from the charger isgreater than an initiation threshold. If not, the demand-based floatcharge continues and the float output voltage setting is set or retainedat 140 and the process returns at 150 to state selection at 110.

If at 130 a determination is made that the current being drawn by thebattery from the charger is greater than an initiation threshold, ademand-based automatic charge cycle begins and a boost output voltagesetting is selected at 160. The process then returns at 150 to stateselection at 110.

However, if at 120 it is determined that the previous output voltagesetting is at a boost voltage (162), then a determination is made at 170whether a current reversion threshold has been reached. If it has not, ademand based automatic charge cycle is initiated, and a boost outputvoltage setting is selected/retained at 180. The process then returns at150 to state selection at 110. If a determination is made at 170 that acurrent reversion threshold has been reached, the demand based automaticcharge cycle ends and a float output voltage is set at 190. The processthen returns at 150 to state selection at 110.

The initiation threshold may be equal to the current limit, or thereversion threshold may be equal to the initiation threshold. Astraightforward implementation of the present systems and methods mayemploy identical current levels for all three settings, initiationthreshold, current limit and reversion threshold.

As illustrated in prior art FIG. 1, standard boost charging method, mayinclude a discharge and recharge cycle, based on an automatic “demandbased” charging method 100. Hence, at some point, the battery is fullycharged and drawing float current from the battery charger (122), whichis operating at its float voltage setting. An event occurs (such asstarting an engine with an electric starter motor powered by thebattery, or powering a continuous DC load) so that the battery is nowpartially or completely discharged. The battery charger's output currentautomatically increases, due to the battery's increased chargeacceptance (130). A demand-based recharge cycle begins (160). During thefirst part of the demand-based charge cycle, the battery chargeroperates at its maximum level (e.g., current limit). While the batterycharger is operating at its maximum level, the battery voltage willtypically remain at a level below the preset charge voltage levels(170). The battery charger's output setting automatically transitionsfrom float voltage to boost voltage because its “demand based” chargingmethod is designed to perform this voltage transition based on thedemand for DC output current (180). As the battery is being recharged,its voltage will gradually increase toward the preset boost setting.Thereafter as the battery is further recharged, the battery charger isgoverned by the boost voltage limiting system, rather than the currentlimiting system. Output current will gradually decrease from its maximumlevel until it reaches a point called the reversion threshold (e.g., 10%of rated output current)(170), at which the battery chargerautomatically and immediately reverts from boost voltage to floatvoltage (190).

Some existing automatic battery chargers include a time limit for thedemand-based charge cycle. Prior art FIG. 2 illustrates a flowchartdiagram of time-limited demand-based automatic boost charge for anauto-charge system and method 200. Therein, if the current remains abovethe reversion threshold until the time limit expires, the demand-basedcharge cycle will terminate. This provides a back-up means thatterminates the recharge cycle if the current remains at a high level foran prolonged time, decreasing the risk of over-charging the battery(e.g., if an unanticipated load exceeds the charge termination current).

Hence, time-limited demand-based automatic boost charge for anauto-charge system and method 200 begins with state selection 210. At212 a determination is made as to whether a demand-based boot timer hastimed-out. If it has not, a determination of the previous output voltagesetting is made at 220. If the charger is at the float voltage (222),then a determination is made at 230 whether the current being drawn bythe battery from the charger is greater than a initiation threshold. Ifnot, the demand-based float charge continues and at 240 the float outputvoltage setting is set or retained and the process returns at 250 tostate selection at 210.

If at 230 a determination is made that the current being drawn by thebattery from the charger is greater than an initiation threshold, a boottimer starts at 255, a demand-based automatic charge cycle begins, and aboost output voltage setting is selected at 260. The process thenreturns at 250 to state selection at 210.

If at 212 a determination is made that the demand-based boot timer hasnot timed-out, but a determination is then made at 220 that the previousoutput voltage setting for the charger is a boost voltage (262), then at266 the boost timer reading is updated, and a determination is made at267 whether the boost timer has expired. If the boost timer has notexpired at 267, a determination is made at 270 as to whether a currentreversion threshold has been reached. If a determination is made at 270that a current reversion threshold has not been reached, a demand basedautomatic charge cycle is initiated or retained, by selecting orretaining the boost output voltage setting at 280, and the processreturns at 250 to state selection 210.

However, if the current reversion threshold has been reached at 270, theboost timer is stopped at 282, and the demand based automatic chargecycle ends with a float output voltage being set at 290. The processthen returns at 250 to state selection at 210.

If at 267, the boost timer has expired, a demand-based boost time-out isset at 292, the boost tinier is stopped at 282, a float output voltageis set at 290, and the process returns at 250 to state selection at 210.

Conversely, if a determination is made at 212 that the demand-basedboost has timed out, the boost timer is stopped at 282, and the demandbased automatic charge cycle ends with a float output voltage being setat 290. The process then returns at 250 to state selection at 210.

Prior art FIG. 3 illustrates a flowchart diagram of fixed extensiondemand-based automatic boost charge for an auto-charge system and method300, which begins with state selection 310. At 312 a determination ismade as to whether a demand-based boot timer has timed-out. If it hasnot timed-out, a determination is then made at 320 of a previous outputvoltage setting for the charger. If the charger is at the float voltage(322), then a determination is made at 330 whether the current beingdrawn by the battery from the charger is greater than an initiationthreshold. If not, the demand-based float charge continues and the floatoutput voltage setting is set or retained at 340 and the process returnsat 350 to state selection at 310.

If at 330 a determination is made that the current being drawn by thebattery from the charger is greater than an initiation threshold, ademand-based automatic charge cycle begins by setting a boost outputvoltage at 360. The process then returns at 350 to state selection at310.

Conversely, if the previous output voltage setting at 320 indicated thecharger is outputting a boost voltage (362), a determination is made at370 as to whether a current termination threshold has been reached. Ifthe current termination threshold has been reached, demand-basedautomatic boost charging continues with the boost output voltage beingselected at 380, and the process returns at 350 to state selection 310.

If at 370 the current has not exceeded the termination threshold adetermination is made at 383 whether an extension timer is stillrunning. If it is not, the extension timer is started at 385,demand-based automatic boost charging continues with the boost outputvoltage being selected at 380, and the process returns at 350 to stateselection 310.

If at 383 it is determined that the extension timer is still running,the extension timer reading is updated at 387 and a determination ismade at 389 as to whether the extension timer has expired. If theextension timer has not expired, demand-based automatic boost chargingcontinues with the boost output voltage being selected at 380, and theprocess returns at 350 to state selection 310.

If at 389 it is determined that the extension timer has expired, a floatoutput voltage is set at 390, and the process returns at 350 to stateselection at 310.

Conversely if a determination is made at 312 that the demand-based boosttime has timed out, a float output voltage is set at 390, and theprocess returns at 350 to state selection at 310.

In any of the above prior systems and methods, at the reversion fromboost voltage setting to float voltage (190, 290, 390), the battery'scurrent draw decreases to a very low level, near zero, and thengradually increases again as the battery enters a final “finishingcharge” period in which it reaches full charge and returns to itsoriginal state in which it draws a normal float current.

Dynamic Demand-Based Automatic Boost Charging Systems

To charge a battery at maximum speed and with maximum safety inaccordance with embodiments of the present systems and methods, batterycharger embodiments transition from boost charge voltage to float chargevoltage at a correct time. The correct time is the point at which thebattery achieves full charge, and before excess overcharge occurs.While, prior art auto boost systems have has been used to estimate thecorrect boost duration, the correct time of transition from boost tofloat mode varies from battery to battery for several reasons. For agiven battery capacity, charger ampere rating, and boost chargingvoltage, the correct transition time will vary. For example, transitionshould occur sooner when charging a battery that is only partiallydischarged versus one that is fully discharged. Also, transition shouldoccur later when charging a battery that is connected in parallel with afixed DC load compared to a battery not connected to a fixed DC load.Transition time should vary depending on varying ampere load of a DCload connected in parallel with the battery. Transition time should alsovary depending on manufacturing tolerances, the battery's age, number ofcharge/discharge cycles, maintenance regime and other batterycharacteristics.

In accordance with various embodiments of the present dynamic boostcharging systems and methods, an automatic determination of the correcttime to transition from boost to float charging mode is made, regardlessof variables affecting the battery. Compared with prior art devices andmethods, the benefits of embodiments of the present dynamic boostcharging systems and methods include that, for a given charger ampererating, the battery will be recharged faster and more completely, withreduced risk of overcharge and consequent risk of emission of hydrogengas, premature loss of electrolyte, and/or shorter battery life.

Embodiments of the present dynamic boost charging systems and methodsmay monitor the magnitude and timing of the battery charger's outputcurrent and use that data to automatically vary the magnitude and timingof the battery charger's voltage setting.

FIG. 4 illustrates a block diagram of dynamic demand-based automaticboost battery charger 400, in accordance with at least one embodiment.Battery charger 400 using embodiments of the present dynamic boostcharging methods is capable of using two or more preset DC voltagesettings such as may be provided by a transformer 402 and relatedcircuitry and components using AC input current 404, float voltage 406and one or more different boost voltages 408. In accordance withembodiments of the present systems and methods for dynamic boostcharging, battery charger 400's preset float and boost voltages (406,408) are both set correctly, neither too high nor too low, for thebattery that will be charged, so that the battery is neitherundercharged nor overcharged in float mode (406) and in boost mode(s)(408). Embodiments of the present dynamic boost charging systems andmethods provide automatic control of a battery charger's output voltage410 and employs the battery charger's internal monitoring and controlcircuitry 412. One component of the battery charger's internalmonitoring circuitry is current sensor 414, which is a device thatmeasures the DC output current being delivered by the charger to a load,which is typically a battery. DC current sensor 414 provides DC outputcurrent data to charge control system 416, which may include one or moremicroprocessors, microcontrollers, Application Specific IntegratedCircuits (ASICs), and/or the like. This DC output current data isemployed for execution of embodiments of the present dynamic boostcharging methods. Charge control system 416 may also be interconnectedwith the battery charger's internal voltage regulation circuitry 418 inorder to control transitions of the voltage setting from float to boostand from boost to float. In addition, clock or timer 420 may be includedto revise timing of the boost-to-float transition, such as by providinga number of timers.

A first timer may measure how long the charger is delivering outputcurrent above a reversion threshold. Since the battery charger “knows”this time period, this data can be used to determine the length of theextended boost time period. A second timer may determine when charger400 reverts from boost voltage 408 to float voltage 406 at the end ofthe extended boost time period, which varies dynamically based upon thelength of the first time period. In accordance with embodiments of thepresent systems and methods, battery 400 charger reverts from boostvoltage 408 to float voltage 406 so that battery charger 400 is notfixed at boost voltage 408 and so that the battery is not overcharged.In accordance with embodiments of the present systems and methods, theinclusion of a dynamically variable time limit for the boost periodaccurately terminates the charge cycle, providing a thorough rechargewith reduced risk of over-charge.

The battery charger's use of a counting means to measure and store timedata, charge data, or both, in accordance with embodiments of thepresent systems and methods, may extend the time that the charger staysin boost mode, before reverting back to float mode. Thus In accordancewith embodiments of the present systems and methods, timing means 420interacts with demand-based control means 416 and with the batterycharger's internal voltage regulation circuitry 418 in order to maketransitions in both directions between preset float voltage 406 andpreset boost voltage(s) 408.

Dynamic Demand-Based Automatic Boost Charging Methods

FIGS. 5A and 5B, together, illustrate an exemplary flowchart diagram ofdynamic demand-based automatic boost charge for an auto-charge systemand method 500, according to at least one embodiment. Beginning in FIG.5A at state selection 510, a determination is made at 520 of a previousoutput voltage setting for the charger. If it is determined that theprevious output voltage setting is at a float voltage (522), then adetermination is made at 530 whether the current being drawn by thebattery from the charger is greater than an initiation threshold. Ifnot, the demand-based float charge continues and the float outputvoltage setting is set or retained at 540 and the process returns at 550to state selection at 510.

If at 530 a determination is made that the current being drawn by thebattery from the charger exceeds an initiation threshold, a dynamiccharge counter is initiated at 555 and a demand-based automatic chargecycle begins, with a boost output voltage being set at 560. The processthen returns at 550 to state selection at 510.

Thus, if at 520 the previous output voltage setting is at a boostvoltage (562), then a determination is made at 566 whether a currentinitiation threshold has been reached. If it has, a determination ismade at 567 whether a dynamic charge count limit has been reached. If ithas not, then at 568 a percent over-charge-time is added to the dynamiccharge counter, a bulk charge is initiated with a demand based automaticcharge cycle. As a result, a boost output voltage setting isselected/retained at 580. The process then returns at 550 to stateselection at 510.

Conversely, if a determination is made at 567 that the dynamic chargecount limit has been reached, then the bulk charge is initiated with ademand based automatic charge cycle, without adding over-charge-time tothe dynamic charge counter. And again, a boost output voltage setting isselected/retained at 580 and the process returns at 550 to stateselection at 510.

Again, at 566, a determination is made whether the current is greaterthan the initiation threshold. Turning to FIG. 5B, if the current isless than the initiation threshold, a determination is made at 585whether the dynamic charge counter has reached zero. If it has, adetermination is made at 570 as to whether a current flowing is lessthan a reversion threshold. Similarly, if it is determined at 585 thatthe dynamic charge counter has not reached zero, the dynamic chargecounter is decremented at 586, and the determination is made at 570 asto whether a current flowing is less than a reversion threshold. If thecurrent is greater than the reversion threshold, an auto-boost isinitiated, with a demand based automatic charge cycle. As a result, aboost output voltage setting is selected/retained at 580. The processthen returns at 550 to state selection at 510.

Thus, if at 570 it is determined that the current flowing is less thanthe reversion threshold, a determination is made at 587 whether dynamiccharging is enabled. If it is, dynamic charge extension takes place anda determination is made at 589 whether the dynamic charge counter hasreached zero. If not, returning to FIG. 5A, auto-boost is initiated,with a demand based automatic charge cycle. As a result, a boost outputvoltage setting is selected/retained at 580. The process then returns at550 to state selection at 510.

Returning to FIG. 5B, if at 587 a determination is made that dynamiccharging is not enabled, or if it is and at 589 a determination is madethat the dynamic charge counter has reached zero, the demand basedautomatic boost charge cycle ends and a float output voltage is set at590. The process then returns at 550 to state selection at 510.

In accordance with embodiments of the present systems and methods, suchas illustrated in FIGS. 5A and 5B, dynamic demand-based automatic boostcharge for auto-charge method 500 may include a discharge and rechargecycle. Therein, at some point, a battery is fully charged and drawingfloat current from the battery charger (522), which is operating at itsfloat voltage setting. An event occurs (such as starting an engine withan electric starter motor powered by the battery, or powering acontinuous DC load) so that the battery is now partially or completelydischarged. The battery charger's output current automaticallyincreases, due to the battery's increased charge acceptance (530).

Thus, various embodiments of the present dynamic boost charging systemsand methods include a discharge and recharge cycle. For example, thebattery may be fully charged and drawing float current from the batterycharger, which is producing float voltage (522). An event occurs (suchas, for example, starting an engine with an electric starter motorpowered by the battery, or powering a continuous DC load) so that thebattery becomes partially or completely discharged. The batterycharger's output current automatically increases, due to the battery'sincreased charge acceptance. When the current reaches the boost chargeinitiation threshold (530), a demand-based recharge cycle begins. Duringthe first part of the demand-based charge cycle, the battery chargeroperates at its maximum level (i.e., “current limit”). While the batterycharger operates in current limit, the battery voltage will typically beat a level below the preset float and boost voltage levels. The batterycharger's voltage setting automatically transitions from float voltageto boost voltage because its “demand based” charging method is designedto perform this voltage transition based on the demand for DC outputcurrent. Typically a battery charger's voltage setting automaticallytransitions from float voltage to boost voltage because its “demandbased” charging method is designed to perform this voltage transitionbased on the demand for DC output current.

Differing from the standard methods, in embodiments of the presentsystems and methods, the battery charger starts an internal timer (555)from the point the demand-based charge cycle starts (560) so that thecharger can measure the duration of the high current portion of thecharge cycle.

As the battery is being recharged, its voltage will gradually increaseto become equal to the preset boost voltage. As the battery is furtherrecharged, the battery charger's output current will gradually decreasefrom its maximum level until it reaches the initiation threshold orother threshold as may be programmed into the control system (566).

Differing from the standard method, at this point in embodiments of thepresent systems and methods, the timer that was previously counting upbegins counting down (567, 568). Until the counter returns to itsstarting value (567), the charge control system will keep the batterycharger's output voltage at boost voltage, regardless of the outputcurrent (580).

In accordance with embodiments of the present systems and methods, time,returned charge, or a combination of both may be used to implementdynamic boost charge extension (587, 589). In some embodiments, theextended boost time increments and decrements are weighted according tothe output current (570). This sets the extended boost period accordingto the returned charge (typically measured by Ampere-hours or Coulombs),rather than according to elapsed time (typically measured by hours,minutes, or seconds). The timer does not necessarily count down at thesame rate at which it counts up, allowing the extended boost time to bea function of the time spent in constant current charge. A linearfraction or multiple of the constant current charge may be employed.Applying a lower limit will ensure at least a minimum amount of extendedcharge always occurs. Applying an upper limit reduces the risk ofover-charge when a battery requires an unusually long constant currentcharge that could occur if there were a large static load in parallelwith the battery, if a large battery were used, etc.

Various embodiments employ a linear function of elapsed time in constantcurrent charge (570), with both lower and upper limits for extendedboost time (587). This embodiment may be highly effective while allowingthe charge control system to be simple and low in cost.

After the extended boost period has timed-out (589), then the batterycharger automatically reverts from boost voltage to float voltage (590)when output current is less than the reversion transition setting (570).

At the reversion from boost voltage setting to float voltage (590), thebattery's current draw decreases to a very low level, near zero, andthen gradually increases again as the battery enters a final “finishingcharge” period in which it reaches full charge and returns to itsoriginal state in which it draws a normal float current.

In some embodiments, a time limit may be included for the demand-basedcharge cycle. If the current remains above the reversion threshold untilthe time limit expires, the demand-based charge cycle will terminate.This further reduces the risk of over-charging the battery. FIGS. 6A and6B, together, illustrate an exemplary flowchart diagram of atime-limited dynamic demand-based automatic boost charge for anauto-charge method 600, according to at least one embodiment. Therein,an additional total time limit, as well as a variable extension time(i.e. two separate timer functions) are employed.

Starting in FIG. 6A, at state selection 610, a determination is made at612 as to whether a demand-based boot timer has timed-out. If it hasnot, a determination of the previous output voltage setting is made at620. If it is determined that the previous output voltage setting is ata float voltage (622), then a determination is made at 630 whether thecurrent being drawn by the battery from the charger is greater than aninitiation threshold. If not, the demand-based float charge continuesand the float output voltage setting is set or retained at 640 and theprocess returns at 650 to state selection at 610.

A dynamic charge counter is initiated at 655, if a determination is madeat 630 that the current being drawn by the battery from the charger isless than an initiation threshold and a boost timer is started at 658,as a demand-based automatic charge cycle begins, with a boost outputvoltage being set at 660. The process then returns at 650 to stateselection at 610.

Conversely, if a determination is made at 620 that the previous outputvoltage setting is at a boost voltage (662), then at 663 the boost timerreading is updated, and a determination is made at 664 whether the boosttimer has expired. If the boost timer has not expired at 664, then adetermination is made at 666 whether a current initiation threshold hasbeen reached. If it has, a determination is made at 667 whether adynamic charge count limit has been reached. If it has not, then at 668a percent over-charge-time is added to the dynamic charge counter, abulk charge is initiated with a demand based automatic boost charge. Asa result, a boost output voltage setting is selected/retained at 680.The process then returns at 650 to state selection at 610.

However, if a determination is made at 667 that the dynamic charge countlimit has been reached, then the bulk charge is initiated with a demandbased automatic boost charge, without adding over-charge-time to thedynamic charge counter. And again, a boost output voltage setting isselected/retained at 680 and the process returns at 650 to stateselection at 610.

Again, a determination is made at 666 whether the current is greaterthan the initiation threshold. If it is not, turning to FIG. 6B, adetermination is made at 685 whether the dynamic charge counter hasreached zero. If it has, a determination is made at 670 as to whether acurrent flowing is less than a reversion threshold. Similarly, if it isdetermined at 685 that the dynamic charge counter has not reached zero,the dynamic charge counter is decremented at 686, and the determinationis made at 670 as to whether a current flowing is less than a reversionthreshold. If the current is greater than the reversion threshold, anauto-boost is initiated, with, returning to FIG. 6A, a demand basedautomatic charge cycle. As a result, a boost output voltage setting isselected/retained at 680. The process then returns at 650 to stateselection at 610.

Returning to FIG. 6B, if at 670 it is determined that the currentflowing is less than the reversion threshold, a determination is made at687 whether dynamic charging is enabled. If it is, dynamic chargeextension takes place and a determination is made at 689 whether thedynamic charge counter has reached zero. If not auto-boost is initiated,returning to FIG. 6A, with a demand based automatic charge cycle. As aresult, a boost output voltage setting is selected/retained at 680. Theprocess then returns at 650 to state selection at 610.

Returning again to FIG. 6B, if at 687 a determination is made thatdynamic charging is not enabled, or if it is and at 689 a determinationis made that the dynamic charge counter has reached zero, the boosttimer is stopped at 682, the demand based automatic boost charge cycleends and a float output voltage is set at 690. The process then returnsat 650 to state selection at 610.

Returning to 664 and FIG. 6A, if the boost timer has expired, ademand-based boost time-out is set at 692 (see FIG. 6B), the boost timeris stopped at 682, a float output voltage is set at 690, and the processreturns at 650 to state selection at 610.

As noted, a time limit may be included for the demand-based chargecycle, such that if the current remains above the reversion thresholduntil the time limit expires, the demand-based charge cycle willterminate, to reduce the risk of over-charging the battery. Thus,returning to FIGS. 6A and 612, if a determination has been made that thedemand-based boost has timed out, the boost timer is stopped at 682 (seeFIG. 6B), and the demand based automatic charge cycle ends with a floatoutput voltage being set at 690. The process then returns at 650 tostate selection at 610.

Hence, in accordance with embodiments of the present systems andmethods, in addition to the usual demand-based boost charge criteria(i.e., reversion transition current and time-out), embodiments of thepresent systems and methods, obtain an initial time or chargemeasurement, determine an appropriate time or charge to complete therecharge cycle based on that measurement, and maintain boost voltageuntil that additional time or charge has been provided. Thus,embodiments of the present dynamic boost charging systems and methodsprovide the time measurement, the calculation, and the execution of anextended boost time period, supplementing typical standard demand-basedboost charging methods used in commercial chargers.

Embodiments of the present dynamic boost systems and methods perform afunction differently as a result of being adaptive. The amount of timethe charger remains in boost mode depends on how long it takes for thebattery's current acceptance to start tapering off.

The standard and dynamic charging methods are similar in that both areautomatic demand-based methods that effect transitions between presetfloat and boost voltages, depending on battery charging current. Theyare different, in addition to other factors, in that embodiments of thepresent dynamic boost charging methods make a time and/or chargemeasurement and stays in boost mode for an additional variable timeperiod that is based on the measured boost time and/or charge requiredfor the initial part of the recharge cycle.

By keeping the battery charger in boost mode for a longer period oftime, in accordance with various above embodiments of the presentsystems and methods, a faster recharge is achieved. By using a variableduration for the extended boost period, which is derived from theobserved initial boost period, the risk of overcharge is decreased.

The first time interval (555, 585, 570, 580) measures how long thecharger is delivering output current above the reversion threshold.Since the battery charger “knows” this time period, this data can beused to determine the length of the extended boost time period. A secondtime interval (555, 585, 570, 587) determines when charger reverts fromboost voltage to float voltage at the end of the extended boost timeperiod, which varies dynamically based upon the length of the first timeperiod. Thereby, battery charger 400 may successfully revert from boostvoltage to float voltage so that the battery charger does not remain ata boost voltage and so that the battery is not overcharged. Theinclusion of a dynamically variable time limit for the boost periodaccurately terminates the charge cycle, providing a thorough rechargewith reduced risk of over-charge.

An exemplary numerical example of use of embodiments of the presentdynamic boost charging systems and methods may employ an initiationthreshold current (530, 630) of 10 Amperes, a reversion thresholdcurrent (570, 670) of 7.5 Amperes, and a dynamic charge extension (568,578) of 50% of the elapsed constant current charge time. This numericalexample is not to be construed as a description of limitations withregard to voltages, currents, and time periods. The embodiments of thepresent dynamic boost charging systems and methods may be capable offunctioning within wide ranges of voltages, currents, and time periods,limited only by the capabilities of the battery charger that is used toexecute the method. A battery charger is attached to a battery and aload (such as a starter motor or continuous DC load). The batterycharger is rated at 10 Amperes DC (in current limit) and is connected toa fully-charged battery which is drawing 0.25 Amperes float current. Theload operates and the battery is therefore partially discharged. At thestart of battery recharge the battery charger's output current increasesrapidly to 10 Amperes and its output voltage setting transitionsautomatically from float to boost. The internal timer startsincrementing (555, 655), to measure the time at high current. After onehour, the battery is partially recharged and the output current fallsbelow the 10 Ampere initiation threshold (566). At this time theinternal timer operation changes from increment mode to decrement mode(567). Twelve minutes later, the current has dropped to 7.5 Amperes atwhich point it would have reverted to float mode if the battery chargerwere using a prior art charging method. Instead, the internal timerkeeps the output voltage at boost voltage for 50% longer (568, 668) thanthe duration between start of boost mode operation and reduction ofbattery current acceptance to less than the initiation value of 10Amperes, making the total boost period 1.5 hours instead of 1.2 hours.At the end of the 1.5-hour time period (589, 689), the battery chargerautomatically reverts from boost mode to float mode and the batteryenters its finishing charge stage. After a few hours, the float currenthas once again stabilized at 0.25 Amperes.

In accordance with embodiments of the present systems and methods fordynamic boost charging the extended boost interval may be configured touse any numerical multiplier. This may be thought of as a percentage,and may be changed from time to time by reprogramming, without affectingfunctions of the methods. For example, if an initial value of 50% isused and later found to be at risk for overcharging some types ofbatteries, this could be reduced to 30% by changing the multiplieraccordingly. Alternatively, if a particular application calls for anaggressive recharge time, and the batteries can perform well withaggressive charging, the multiplier could be increased from 50% to 75%.Making a change to these values does not change any functional aspectsof the method.

Operation

In operation, in chargers that implement embodiments of the presentdynamic boost charging methods, a user may select, by way or example,“Standard demand-based auto equalize”, or “Dynamic demand-based autoequalize,” settings on a charger by using a keypad located on a frontdoor of the charger, or the like. The user may navigate to an “autoequalize” menu and use keypad up/down arrows to make the selection.After the selection of “Standard” or “Dynamic” is made, battery chargingoccurs automatically, in accordance with embodiments of the presentsystems and methods, with no need for manual adjustments or operatorintervention.

The battery charger is connected to an adequately functioningrechargeable storage battery of the correct type and polarity to performbattery charging within an acceptable range of temperatures, which arespecified by the battery manufacturer. As noted, for temperatures thatare more than 5 degrees C. higher than recommended or lower than 25degrees C., automatic temperature compensation may be used. Automatictemperature compensation is a feature that may be available in chargersemploying the present systems and methods for dynamic demand-basedcharging. Such temperature compensation causes the battery charger'soutput voltage to be incrementally higher at lower ambient temperatures,and incrementally lower at higher ambient temperatures. The purpose oftemperature compensation is to neither undercharge nor overcharge abattery.

Alternative Embodiments

Embodiments of the present dynamic boost charging method may be employedin more-or-less typical microprocessor-controlled battery chargers, byemploy appropriate firmware embodying embodiments of the present systemsand methods. This could be implemented on different types ofmicroprocessors and microcontrollers, and with different softwarecoding, as long as the method operates in a substantially similarmanner. When implemented by firmware, it would be possible to writedifferent firmware to be compatible with different types ofmicrocontrollers into which it is loaded. When implemented by firmware,that implementation could use binary instruction codes or any moreabstract programming language, by a micro-program for a programmablestate machine, or as a hardware description language for programmablelogic circuits. As one of ordinary skill in the art will appreciate, itmay be that different instances of firmware use different approaches tohow functions are used and combined. Embodiments of the present systemsand methods for dynamic boost charging method may be implemented intransformer-type battery chargers, in switchmode battery chargers, inelectro-mechanical chargers (such as engine-driven alternators), and anyother charging device with controlled output voltage. Embodiments of thepresent systems and methods for dynamic boost charging method may beimplemented in on battery chargers designed to charge batteries (orbattery sets, or battery strings, or battery stacks) of differentvoltage ratings and ampere-hour capacities and different batterychemistries including various types of lead-acid and nickel-basedstorage batteries. Embodiments of the present systems and methods fordynamic boost charging method may be implemented using a circuitcomprised of standard logic elements instead of a program for amicrocontroller or microprocessor. Embodiments of the present systemsand methods for dynamic boost charging method may be implemented usingan integrated circuit implementation of the standard logic elements,such as a field-programmable gate array (FPGA), Application-SpecificIntegrated Circuit (ASIC), or the like. Embodiments of the presentsystems and methods for dynamic boost charging method may be implementedusing mechanical means, such as a clockwork timer, tally counter(similar to an automotive odometer), a mechanical calculating device(similar to those used in adding machines), etc. Embodiments of thepresent systems and methods for dynamic boost charging method may beimplemented using electro-mechanical means, such as a stepping relay,electro-mechanical tally counter (as used for score counters inelectro-mechanical pinball machines), etc.

In accordance with various further embodiments of the present systemsand methods, dynamic charge duration may be set according to accumulatedcharge (Ampere-hours) instead of, or in addition to, the accumulatedrecharge time (minutes). Time required to safely recharge a battery maybe further reduced by monitoring the battery's current acceptance(and/or other additional parameters and conditions) and keeping thecharging voltage at the highest level possible throughout the durationof the recharge cycle without overcharging the battery. Some benefit maybe derived from using a range of continuously variable charging voltagesrather than two discrete voltage levels called float and boost, inaccordance with some embodiments of the present systems and methods.

Because embodiments of the present dynamic boost method can measure theapproximate state of charge of a battery based on its charge acceptance,embodiments of the present systems and methods may be used to determinebattery health, battery maintenance requirements, and to makepredictions regarding end of the battery's service life.

Above-discussed embodiments of the present dynamic demand-based boostcharging systems and methods are described as using a microprocessor,microcontroller, or the like, in conjunction with software, firmware, orthe like, such as for cost and size reduction. However, as noted,alternate implementations, such as, but not limited to mechanicalcounters, clockwork timers, and combinations of such devices, canimplement embodiments of the present dynamic demand-based boost chargingsystems and methods.

Although the above embodiments have been described in language that isspecific to certain structures, elements, compositions, andmethodological steps, it is to be understood that the technology definedin the appended claims is not necessarily limited to the specificstructures, elements, compositions and/or steps described. Rather, thespecific aspects and steps are described as forms of implementing theclaimed technology. Since many embodiments of the technology can bepracticed without departing from the spirit and scope of the invention,the invention resides in the claims hereinafter appended.

1-5. (canceled)
 6. A dynamic boost charging method, comprising:measuring total DC current and/or battery current with a monitoringcomponent; transmitting output data of the DC current measured by themonitoring component to a battery charger control system; determining aninitial charge time by the battery charger control system; determining,by the battery charger control system, a time to complete a rechargecycle and/or a charge to complete a recharge cycle, based on the outputdata of the DC current measurement; selectively producing a chargingcurrent from at least two preset DC voltage settings with the batterycharger control system, one of the at least two preset DC outputvoltages being a float voltage, and another of the at least two presetDC output voltages being a boost voltage; and maintaining boost voltagefor the determined time to complete a recharge cycle and/or until thedetermined charge to complete a recharge cycle has been provided.
 7. Thedynamic boost charging method of claim 6, wherein selection of DCvoltage settings is performed by the battery charger control systemwhich includes a DC current sensor integrated with the monitoringcircuitry of the battery charger control system.
 8. The dynamic boostcharging method of claim 6, further comprising computing a given time totransition between boost voltage and float voltage with the batterycharger control system, and recharging the battery at a faster rate andwith greater returned charge with the given time than a non-computedtime period.
 9. The dynamic boost charging method of claim 6, furthercomprising monitoring a magnitude and a timing of output current of theselectively used two preset DC output settings with the battery controlsystem.
 10. The dynamic boost charging method of claim 6, furthercomprising computing the transition between boost voltage and floatvoltage settings with the battery charger control system using timeand/or returned charge. 11-20. (canceled)